The present invention relates to a method and furnace construction to be used in processes for producing easily volatile metals from their sulfides. The furnace construction comprises two closely connected furnaces, a reduction furnace and a converter, which are operated at normal pressure, so that the material transfer therebetween is arranged to take place continuously by means of at least one channel provided in between the furnaces. As a result of chemical reactions taking place in the furnaces, the hydrostatic pressure of the furnaces changes. In addition, volumes of the melt layers in the furnaces change. Circulations via at least one channel resulting from these changes at the same time bring about recycling of sulfide matte from the reduction furnace to the converter, which is needed in the process, as well as the recycling of molten metal from the converter to the reduction furnace. Simultaneous flows in opposite directions are produced.